Electronic devices such as central processing units (CPUs) of computers generate large amounts of heat during their normal operation. The heat must be quickly recovered to prevent the CPUs from becoming overheated or damaged due to heat. Typically, a heat sink is attached to a CPU on a circuit board to facilitate removal of heat from the CPU, and a fan unit is provided to the heat sink for circulating air across the heat sink so as to enhance the heat removal rate of the heat sink.
In order to keep the heat sink intimately contacting the CPU on the circuit board, a retaining device is usually used for attachment of the heat sink to the CPU. In most cases, the heat sink combined with the retaining device is attached to the CPU via the retaining device engaging in holes defined in the circuit board or with protrusions formed at lateral sides of a socket connecting the CPU to the circuit board Prior to the heat sink being attached to the CPU via the retaining device, the orientation of the heat sink on the CPU is predetermined and unadjustable. However, many different situations will impact on the cooling efficiency of the heat sink greatly. Examples of such situations are different layouts of components within a computer system, installation of system fans in the computer system, the locations of air intake hole and air exhaust hole defined in a computer enclosure of the computer system for circulation of air across the computer system, etc. These situations will also cause the flowing of air from the system fans to conflict with the air current from the fan unit of the heat sink within the computer enclosure. Therefore, the heat sink and the fan unit on the CPU need to be conveniently adjusted to desired orientations for purposes of dissipating heat more efficiently.